1. Field of the Invention
This invention relates to a universal wheeled assembly which can be easily and releasably attached to conventional line-type powered grass trimmers, in order to selectively convert them into wheeled lawn mowers without affecting their trimming ability when they are hand held.
2. Description of the Prior Art
Line-type grass trimmers have been known and used for many years. From their introduction, their use spread very rapidly to become common household tools. They are particularly attractive to home owners with small yards because they can be used to trim around obstructions and to mow grass in unobstructed areas as well. In addition, their relatively small size compared to regular lawn mowers makes them easy to store, especially for town home owners who prefer to have a single, modestly priced electric trimmer, to accomplish both trimming and mowing operations, rather than have a separate lawn mower and a separate trimmer.
A typical such electric trimmer has an electric cord extending through a hollow tubular shaft at the bottom end of which is a motor housing surrounded by an enlarged peripheral skirt portion. Protruding from the bottom of the motor housing and coupled to the motor's shaft is a grass-cutting head having a circular rotor to which is attached interiorily thereof, a plastic line that provides to the exterior a constant-length line segment which acts as the cutting element for the trimmer.
A grip handle allows one hand of the user to support and guide the grass-cutting head in spaced relation to the ground and into the grass patch to be cut. A motor-control handle at the uppermost end of the shaft and above the grip handle allows the other hand to control the operation of the motor.
Such hand held operation is characterized by a grass cut of uneven height, because it is difficult for the operator to continuously maintain the cutting head at the same height above the ground.
Also, the weight of such trimmers has proved to be an impediment to their use. The weight of a trimmer can contribute to the user's early fatigue, especially when it is used over steep terrain, and where it is difficult for the operator to maintain a balanced foothold.
From their early introduction, there was therefore a continuous need to mount such trimmers on wheels in order to prevent early operator fatigue and to obtain a uniform and even-height grass cut. That need and the various solutions offered to fill that need are described in one or more of the following illustrative U.S. Pat. Nos. 4,442,659; 4,428,183; 4,411,126; 4,389,836; 4,343,139; 4,341,060; 4,287,709; 4,182,100; 3,996,729; 3,774,379.
In general, the known wheeled, trimmer-type lawn mowers have one or more of the following drawbacks: they are cumbersome for use over irregular and obstructed landscapes because they require that the operator use both of his hands: one to hold the motor-control handle of the trimmer, and the other one to steer the trimmer with the handle which is on the wheeled carriage on which the trimmer is mounted; they require too many parts and therefore are too expensive to make; they are not universal in the sense that they are designed to accommodate only a particular type of trimmer; they are bulky and require excessive storage space; they make it relatively difficult to mount and dismount the trimmer on and from the wheeled carriage and such mounting typically requires tools; and users, especially women find it hard to adjust the inclination of the trimmer's shaft and the elevation of the cutting head above ground.
Accordingly, it is a main object of this invention to overcome the above-mentioned and other known drawbacks of known line-type lawn mowers, and to provide a novel universal wheeled assembly in order to allow the operator of a conventional grass trimmer to instantaneously change it from wheel-mounted mowing to hand-held trimming, and vice versa.
It is another object of this invention to provide a new and improved wheeled, trimmer-type lawn mower which employs the motor-control handle on the shaft of a conventional trimmer for a dual purpose: the conventional purpose of controlling the trimmer's motor, and the added purpose of steering a wheeled frame which has no handle, and to which frame the conventional trimmer becomes releasably jointed in a well-balanced manner by a two-part joint, one joint part being positioned on the trimmer shaft without modifying the shaft in any manner whatsoever, and the other joint part being mounted on the wheeled frame; which allows the one part to remain on the shaft permanently without interfering with the functioning of the trimmer when it is separated from the frame; which requires no tools to make or separate the joint between the frame and the trimmer shaft; and which is simple in design, compact in use, light-weight, and inexpensive to manufacture.